How do the headwaters of the Mississippi River differ from its lower course?

The headwaters and the lower course of the Mississippi River differ significantly in their physical characteristics and environmental behavior:

• Headwaters: From its source at Lake Itasca to the head of navigation at St. Paul, the river is a clear, fresh stream. It winds through low countryside characterized by lakes and marshes, maintaining an unassuming nature.1
• Lower Course: Below the confluence with the Ohio River, the river attains its full grandeur, becoming a brown, lazy, and massive waterway that is often 1.5 miles wide. It is a classic example of a meandering alluvial river, featuring a channel that loops and curls across its floodplain, creating oxbow lakes, cutoffs, and swampy backwaters.1

While the headwaters are defined by their relatively quiet, clear flow through glaciated terrain, the lower course is a heavily modified, sediment-laden system shaped by human engineering, such as levees and dams, and the massive discharge received from major tributaries.12